The present invention relates to an apparatus for separating particle-laden gas into a gas and particles which is especially adapted for removing dust from dust-laden gas or particularly adapted for use in a process for calcining cement or alumina particles.
For instance, in the cement calcination process, the cyclone as shown in FIG. 1 has been widely used for separating and heating particles of raw materials because of its high separation efficiency and simple construction. However, because of its underlying principle, the cyclone a has an inevitably high pressure loss. For instance, in the case of a single stage, the pressure loss ranges from 100 to 150 mmAq and in the case of a four serial stage, the pressure loss ranges from 400 to 600 mmAq. As a result, the power consumption of blowers and exhaust fans increases. In operation, a high temperature gas laden with particles flows through an inlet duct b tangentially into the cylindrical portion of the cyclone a at the inlet velocity of from 10 to 20 meters per second. Because the cylindrical portion has a top wall c and a gas outlet pipe d, the gas is forced to spiral downward along cylindrical and conical walls e and f while the particles, by virture of their inertia, are flung against them. Thereafter the gas spirals upward at the inside of the downward spiralling gas vortex and flows into the gas outlet pipe d. The pressure loss across the cyclone a is therefore mainly due to the energy loss due to the forced formation of this double vortex. In general, the pressure loss is in proportion to the square of the velocity of the gas at the inlet. It follows therefore that when the inlet velocity or head is extremely reduced to the order of less than 10 meters per second, the pressure loss can be considerably decreased, but the cyclone must be increased in size accordingly. Therefore this scheme is unsatisfactory in practice.
In view of the above, the primary object of the present invention is to provide a particle separator in which a top wall is spaced upwardly apart from an inlet by a suitable distance so that an upper space may be defined between the inlet and the top wall, whereby the pressure loss can be considerably reduced.
The present invention will become more apparent from the following description of a preferred embodiment thereof taken in conjunction with the accompanying drawings.